These cans scale really well so better/more powerful amps will make it sound a lot better, how much better? that's up to your ears. The 650 sound decent straight from a PC/Ipod to me, sounded a lot better with a Magni 2, and even better with a friends Jotunheim through SE.

If you want the full package, use fulla 2 as your dac into a magni 3 (unless you want to drop bonus cash on a modi or something). The fulla 2 will get the 6xx loud enough, but you will lose some clarity and you won't get the full signature hd 650 sound.

As E111 said, these will scale and you'll be upgrading for awhile. These headphones have unlimited scaling potential. Fulla 2 is good enough, but you would get improvements with dac/amps in the thousands of $'s range.

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tessierpg

1y

Erosis

Use the SDAC as a dac, 79$. Or the O2/SDAC combo 149$. Unbeattable at that price.

To get "the most" you almost definitely need more. To get enough to be happy, you may not. The Fulla doesn't have enough output to really push highly dynamic content out properly at higher levels. If you don't listen to things with lots of dynamics, no problem. If you listen quietly, you may be fine as well.
To give yourself some headroom, and allow for full output of things, you could use more power. Once you hit certain levels of power, more doesn't accomplish much of anything on its own. It comes down to distortion, speed, etc. which becomes incredibly subjective and a very personal decision. The best objective design may fail horribly next to something that doesn't measure as well, but leads to more enjoyment for you.
Basically, look for more powerful amps first, if you decide you need more after hearing it. You may be happy enough not to chase after more right away. But there are lots of powerful amps out there now, so you can get sort of picky with them if you get into something with power to spare.
Obviously, I didn't mention DACs at all. Those scale as well, but I think the lack of output power will bother you before the DAC in the Fulla will.

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tessierpg

1y

ProfessorPat

Fulla2 is a good starting point, delivering 40mw into 300 ohms, which is by the way about 4x the necessary power to drive the HD6xx to more than enough db in volume level. If you are only going to amp the HD6xx, then there is absolutely no need for a more powerful amp. Yes there are higher priced amps available, there are higher quality amps available, but it’s objectively all you need in terms of power in mw, since the HD6xx‘ SPL is rated at 103db/V. And a well reputable AKM DAC is also included inside. All for a reasonnable price of 99$. For a little more $, I also recommend the Massdrop O2/SDAC combo, which drops at 149$, and will most probably redrop before christmas. The O2 is more powerful and well designed, with a Grace SDAC inside (an AKM AK4452). It has also gain control (1x/3.3x) which suits the 2v output of the DAC. You may bypass the DAC with a line input or bypass the Amp with a line output in DAC mode. But then again, if you are on a budget, the Fulla2 is more than powerful enough to drive the HD6xx and has its own DAC too, an AK4490. Or you can go with a Schiit stack, but it will be more expensive, and not necessary a better choice than the Fulla2 if you don’t need the power. The Schiit Stack (Magni3/Modi) is good, but more expensive (200$ or more depending on version purchased) but not necessarily better than the O2 combo which is 149$ in the Massdrop version (a lot more in the JDSLabs or other versions).

You'd have to be listening at lower than average volumes with 40mW. They are optimal at 63mW at 300 - 500 ohms, if the amp isn't giving 63mW at 500 ohms, it's not so likely it's going to give 63mW at 300 ohms.

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tessierpg

1y

Jackula

The power required is relative to SPL level of a particular headphone, whatever its impedance. The 6xx is 300 ohms and has an SPL of 103db/V. To attain 110db, which is too loud to sustain for long periods, it therefore needs 16.7mw under 300 ohms. For moderate listening, at 100db (which is already high enough), the 6xx needs less than 2mw of power under 300 ohms. The Fulla2 may provide 40mw under 300 ohms. It’s a simple fact. It’s a myth that the HD650/6xx needs a lot of power because of its high impedance. It simply needs an amp that can drive it at 300 ohms (with very low power requirement). Dont forget that the DAC´s output is normally at 2v. I agree that if the source output is very low, under 0,7v, then you may need a bit more power than what i’ve said above, but the Fulla2 has a lot of buffer/headroom at 40mw rated power under 300 ohms.
Check it for yourself: http://www.digizoid.com/headphones-power.html

115dB is the target, it's not sustained, it allows your harmonics to reach those levels without clipping. Listening at 80dB will have harmonics reaching 115dB. The HD6XX is 103dB/V which works out to be roughly 97dB/mW. 40mW gives you 109dB's of SPL maximum, you have about 6 dB that will clip when listening at 80dB RMS.
And like I said, if the amp scales linearly (not current capped), it will need 105mW because mid-bass is 500 ohms. It's not a myth, you just got your maths wrong.

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tessierpg

1y

Jackula

We have different volume targets, that’s all. I prefer to preserve my ears. Anything over 20mw is clearly dangerous with the HD6xx.

You can probably go higher than 70dB without clipping, but it does require music to have a more limited dynamic range. Obviously, I agree with your side of this, as we went through this same thing with the HE4XX discussion and other amps (though that one was easier without the inductance of the voice coil to worry about).
The point of all of it is headroom. You can't assume listening at 83dB means you only need enough power to drive it to 83dB. You need enough for that plus all peaks over your average listening level. As I said originally, 40mW may be enough depending on what you listen to and how you listen, but enough to have a safe buffer is definitely not a bad idea, as this is "conditionally" enough power.

I don't disagree. That's why I said at the very top of this thread that it will probably be adequate, however I don't agree when someone barges in and says 40mW is 4x the power requirements of these headphones. It is not factually correct.
As you probably know, it's not all about power either. There's good power and there's bad power, so we can talk specs all day, but at the end of the day listening counts and everyone have their own preferences.

Right. Pretty much my point exactly. But determining "requirements" is so arbitrary here that I don't know how to objectively state a "power requirement" for them... I mean 10mW does make sound. And as you said, different things make power in ways that affect this number too, so trying to quantify anything definitively as necessary or ideal or anything else is overly difficult.
Either way, I completely agree: Listen for yourself and make a decision.